diff --git a/sys/riotboot/Makefile b/sys/riotboot/Makefile
index 344672d2e2..448312b317 100644
--- a/sys/riotboot/Makefile
+++ b/sys/riotboot/Makefile
@@ -2,6 +2,8 @@ SUBMODULES := 1
 
 ifneq (,$(filter riotboot_slot,$(USEMODULE)))
     CFLAGS += -DSLOT0_OFFSET=$(SLOT0_OFFSET)
+    CFLAGS += -DSLOT1_OFFSET=$(SLOT1_OFFSET)
+    CFLAGS += -DNUM_SLOTS=$(NUM_SLOTS)
 endif
 
 include $(RIOTBASE)/Makefile.base
diff --git a/sys/riotboot/slot.c b/sys/riotboot/slot.c
index 09cac62a78..4d38e6568d 100644
--- a/sys/riotboot/slot.c
+++ b/sys/riotboot/slot.c
@@ -33,6 +33,9 @@
  */
 const riotboot_hdr_t * const riotboot_slots[] = {
     (riotboot_hdr_t*)(CPU_FLASH_BASE + SLOT0_OFFSET),   /* First slot address -> firmware image */
+#if NUM_SLOTS == 2
+    (riotboot_hdr_t*)(CPU_FLASH_BASE + SLOT1_OFFSET),   /* Second slot address -> firmware image */
+#endif
 };
 
 /* Calculate the number of slots */